Surgical stapler

ABSTRACT

A hand-held surgical stapler is provided having a reduced distal profile due to a unique feeding means. A combination of features allows the reduced distal profile. The staple storage cover can be of reduced distal thickness due to the slope effect. The staple pusher has the capability at its distal end to push and by pushing lift all of the staples, including the last, into the staple track. Provisions are made on the staple pusher to allow the form tool to displace it out of the staple track to allow forming of the last staple. Nose assemblies are disclosed which can be interchangeably mounted to various trigger assemblies. The pre-load on the stored staples can be varied. A ratchet feature requires full depression of the trigger before it can be returned to a neutral or extended position and full extension of the trigger to its neutral position prior to initiation of the next staple feed cycle.

This is a continuation of copending application Ser. No. 07/740,505filed on Aug. 5, 1991 now U.S. Pat. No. 5,170,926.

FIELD OF THE INVENTION

The field of this invention relates to hand-held surgical staplers.

BACKGROUND OF THE INVENTION

Hand-held surgical staplers have been in use for some time. Thesestaplers feature a magazine to store staples prior to dispensing, amechanism to feed staples, and another mechanism to form them as theyare discharged from the apparatus.

From an ergonomic point of view, the hand-held stapler needs to have alow distal profile to allow the surgeon maximum visibility of theclosure site as the staples are formed to close in incision. Anotherimportant criteria for surgical staplers is the ability to reliably feedstaples as needed without clogging or jamming. The need to reliably feedstaples exists concerning the first staple to be fed in a series all theway down to the last remaining staple in the magazine.

Another desirable feature would be an interchangeable feature allowingdifferent nose assemblies to be used with a trigger assembly tofacilitate continuing use of the apparatus during a closure procedure.The interchangeable feature also allows flexibility in production sincea nose assembly would be usable with a variety of handle assemblies.This advantageous feature is incorporated in the apparatus of thepresent invention. Also, a feature of the apparatus of this invention isa layout of the staple track permitting a narrow or distal profilepromoting visibility of the incision. The staple delivery method hasbeen improved to reliably feed staples down to the last staple in thetrack so that the apparatus functions reliably.

The apparatus of the present invention is configured to allow maximumwound site access and staple visibility during placement and formationof the staple. The apparatus has a capacity for storage of a largenumber of staples which is a practical convenience for the surgeon. Dueto the overall simple design of the stapler of the present invention, itcan be economically built for reliable operation. Compactness of therotating head stapler of the present invention, especially at the distalend, is a significant attribute.

The apparatus contains a high capacity staple track. The staples arestacked against each other on end to allow storage of as many staples aspossible in a compact space. Some prior art designs stored the stapleslaying on their sides flat, as on a table, one behind the other. Whenstored in such manner, the capacity of a stapler is significantlyreduced. To ensure compactness in the apparatus of the presentinvention, the staple track is oriented back along a plane roughlyparallel to the form tool plane. To form the staples, they must beoriented into the firing position where the form tool can move themagainst the anvil for staple formation.

To this end, the apparatus of the present invention involves a uniquemanner of reorienting the staples into the firing position. To do this,the staples must be moved around a curved portion at the distal end ofthe staple track and through an opening into the path of the form tool.To accomplish this in the prior art, the staple pusher has been madeflexible so that the last few staples can be pushed around the curvedportion of the staple track. The staple pusher has to be flexible enoughto move in the curved portion of the track. While use of a smallerradius at the distal portion of the staple track reduces the distalprofile of the stapler, it creates more difficulties in producing astaple pusher flexible enough to traverse the smaller radius curveswithout excessive friction.

The approach in the prior art has been to utilize a relatively largeradius at the distal end of the staple track and to orient the stapletrack in an angled manner of approximately 15° from the form tool plane.This resulted in a very bulky rotating distal portion. Another problemwith the use of fairly small radiuses at the distal end of the stapletrack is that the staples in the track are pre-loaded toward the distalend of the track. One way to accomplish the pre-load is to locate acompression spring at the proximal end of the staple stack. It thenfollows that the pre-load will be at its lowest for the last few staplesin the stack. If this decrease in pre-load for the last staples iscoupled with the need to advance those last staples around a fairlysmall radius bend, a significant design constraint is presented forstaplers of the prior art. The stapler of the present invention hassolved this problem by virtue of its features disclosed with regard tothe sloping of the staple track with respect to the form tool path. Thesloping of the staple track allows the staple cover to be thinner at itsdistal end. This reduces the height that the staples must be picked upat the distal end of the staple track to get them into the form toolpath. It is this feature, coupled with the staple pusher incorporating a"fin" design, that allows the apparatus of the present invention toreliably feed all of the staples in the track into the form tool path.The fin is uniquely shaped to reliably feed up to the last staple andthe staple pusher is configured so that the fin is deflected out of theform tool path by the advancing form tool.

By providing these features, the stapler of the present inventionovercomes the design limits of prior designs in solving the problem ofbeing able to reliably feed staples up to the last staple in a feed pathinvolving a small radius bend at the distal end of the staple track.

Prior designs of surgical hand-held staplers are illustrated in U.S.Pat. Nos. 4,951,860; 4,662,555; and 4,807,628. These patents showstaples stored on a track being fed into a feedpath and finally pushedagainst an anvil where they are formed and ejected from the stapler.

FIGS. 3 and 4 of U.S. Pat. No. 4,662,555 illustrate a feature whichrequires completed motion of the trigger handle in either directionbefore it can be reversed. With this feature, the trigger must bedepressed completely before it is allowed to be returned to its neutralposition. This allows the surgeon some flexibility while the staple isnot fully formed to position the gun prior to full closure of thestaple. The requirement that the trigger must come all of the way outbefore the next cycle can begin prevents misfeeding of staples into thestaple track.

Other hand-held surgical staplers having one or more of these featurescan be seen in U.S. Pat. Nos. 4,391,402; 4,196,836; 4,592,498;4,523,695; 4,598,711; 4,049,177 (tag attaching apparatus); and EuropeanPatent Application 0040157.

Also, of general interest in the attachment art, are U.S. Pat. Nos.4,077,557 (illustrating a tool used in producing printed circuitassemblies); 4,125,215 (showing a tag attachment apparatus); and2,228,778 (illustrating a desktop stapler).

SUMMARY OF THE INVENTION

A hand-held surgical stapler is provided having a reduced distal profiledue to a unique feeding means. A combination of features allows thereduced distal profile. The staple storage cover can be of reduceddistal thickness due to the slope effect. The staple pusher has thecapability at its distal end to push and and by pushing lift all of thestaples, including the last, into the staple track. Provisions are madeon the staple pusher to allow the form tool to displace it out of thestaple track to allow forming of the last staple. Nose assemblies aredisclosed which can be interchangeably mounted to various triggerassemblies. The pre-load on the stored staples can be varied. A ratchetfeature requires full depression of the trigger before it can bereturned to a neutral or extended position and full extension of thetrigger to its neutral position prior to initiation of the next staplefeed cycle.

DETAILED DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 1A are exploded views of the apparatus of the presentinvention.

FIGS. 2 and 2(A-B) are front, side, and top views of the staple pusher.

FIGS. 3 and 3(A-B) are side, top, and end views of the staple track.

FIGS. 4 through 8 is a side elevational view of the staple pushershowing sequentially how the last two staples in the staple track arefed into the staple path for formation.

FIGS. 9 through 11 illustrate the snap fit between the nose assembly andthe trigger assembly.

FIGS. 12 and 12(A-B) are front, side, and top views of the staple trackcover.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The disclosures in U.S. Pat. Nos. 4,951,860; 4,807,628; and 4,662,555are incorporated in this application in full.

Some of the details of the operation of the apparatus A are illustratedin FIGS. 16-19 of U.S. Pat. No. 4,951,860. Briefly, to review, theapparatus A as shown in FIG. 1, there are handle portions 10 and 12which are made to be pushed together to form the trigger housing of theapparatus A. Inside the housing portions 10 and 12 is a pivot pin 14which extends through trigger 16. The leading edge 18 of trigger 16extends beyond joined housing halves 10 and 12. It is depressed inwardlyto actuate the apparatus A. Trigger 16 pivots on pin 14 when surface 18is grabbed by the surgeon's hand and depressed inwardly. The pivotaction results in displacement of drive block 20 which is connected totrigger 16 at tab 22. Tab 22 loosely fits inside a slot 24 in driveblock 20. Depressing trigger 16 moves drive block 20 distally againstform tool 26. Form tool 26 reciprocates over track cover panel 28. Trackcover panel 28 has a slot 30 to accommodate the distal end of spring 32.The distal end of spring 32 bears on a stop (not shown) in upper barrelhousing 34. Depressing the trigger 16 inwardly pushes drive block 20distally against form tool 26, compressing spring 32. Release of thetrigger 16 allows spring 32 to push the form tool 26 proximally againstdrive block 20 pushing trigger 16 outwardly.

The housing 34 has a mating section 36 which is shown in detail in FIG.3. Housing 36 includes a staple track 38. Staple track 38 accommodatesstaples 40 having the configuration shown in FIG. 1. The series ofstaples 40 housed in staple track 38 are pushed distally by staplepusher 42 shown in detail in FIG. 2. The staple pusher 42 is biased by aspring 44 which is mounted over a guide 46. Guide 46 has a pair ofoffset outwardly biased tabs 48 which are adapted to be engaged ingroove 50 (see FIG. 3). It is within the scope of the invention toprovide multiple grooves 50 offset from each other to accommodate aloading of different amounts of staples in the staple track 38.Additionally, the amount of pre-load on spring 44 can be adjusted byusing a multiplicity of grooves 50 to provide initial compression tospring 44 depending on the number of staples loaded and in whichparticular groove 50 the tabs 48 are set to engage. After setting thestaples in the staple track so that their legs 52 (see FIGS. 1, 3, and4) extend into troughs 54 which extend from staple track 38, the cover28 is installed into housing 36. Details of the cover are illustrated inFIG. 12.

An important feature of the inclined portion 58 of the staple track 38is that it accommodates the use of the "fin" or tab 112 on the top ofthe staple pusher 42 (see FIG. 2). In order to perform its function, fin112 must bridge the distance between the staple track 58 and the formtool path 56 (see FIG. 8). Due to the incline in staple track 58, thisdistance is reduced at the point of feed. The fin 112 must travel in aclearance slot 61 (see FIG. 12) cut into the staple cover 28 whichseparates the staple track 58 and the form tool path 56. If the staplecover 28 were of a constant thickness, the required clearance slot wouldsplit the cover 28 in two, destroying its functionality. The variablethickness, i.e., the taper/incline of the cover panel 28 prevents this.The distal taper in the staple cover 28 allows structural strength inthe proximal portion of the staple track cover 28. This rigiditybolsters the strength of section 36 and prevents staple binding due towarpage of the staple path in the track 38 if section 36 flexes. Thethick proximal end allows the additional rigidity. The thinner distalend reduces the lift height of the staples while still allowing use of agroove to accommodate the fin or tab 112 which travels in the groove orslot 61. A split cover 28 can be used to accommodate tab 112 but theadvantages of additional rigidity would not be present.

Another feature of the invention is illustrated by a detailed review ofFIGS. 3 and 10. Looking at the elevation view in FIG. 3, it can be seenthat the staple track 38 for its proximal portion is parallel to thestaple form path 56 (see FIG. 3). Thereafter, there is an upwardtransition, preferably at about five degrees (5°) toward form path 56for the distal portion of the staple track 38. This portion of stapletrack 38 that is upwardly inclined is identified by numeral 58. Theupwardly sloping portion 58 of staple track 38 allows reduction of theprofile of track cover panel 28 at its distal end as shown in FIG. 12.The cover 28 has a tapered portion 60 whose angle of taper generallyconforms to the angle of staple track 38 at the inclined portion 58. Itcan then be seen in FIGS. 1 and 3 that the profile of the nose portion62 is reduced due to the inclination of the staple track 58. Furtherreduction in the distal profile at nose 62 is accomplished by a taper 64in housing 34 as shown in FIG. 1.

As previously stated, the form tool 26 is pushed distally by drive block20. Form tool 26 has a lug 66 which extends upwardly into slot 68 ofdrag tool 70 (see FIG. 1). Slot 68 is longer than lug 66 to allowrelative movement between form tool 26 and drag tool 70. Form tool 26has a notch 72 between a pair of lands 74. The lands 74 bear againstcrossbar 76 of staple 40 and move the staple distally against anvil 78.Anvil 78 is fixedly mounted to housing member 34 and has an abutmentsurface 80 which is situated in alignment with notch 72 so that forwardmotion of the drag tool 26, pushing a staple 40 in form path 56, resultsin lands 74 bending the staple around abutment surface 80 which projectsinto the form path 56.

Drag tool 70 has a pair of fingers 82 disposed on drag tool 70 to dragin the path 56 so that upon proximal movement of form tool 26 after ithas reached its full distal movement a gap exists in the plane of path56 between fingers 82 and lands 74. The staple pusher 42 pushes thestaples in track 58 forward in such a manner that as the form tool 26moves proximally from its most distal position, the gap between fingers82 and lands 74 positions itself above the crossbar of the next staple76. The pushing action of staple pusher 42 moves the crossbar 76 of thenext staple 40 into path 56 and into the gap between fingers 82 andlands 74. The staple 40 is then further drawn proximally awaiting asubsequent depression of trigger 16 to repeat the cycle. To ensure thata gap is in fact formed when form tool 26 moves in a proximal direction,the slot 68 is made larger than the lug 66 allowing fingers 82 to lagbehind the proximally advancing form tool 26 so that the next staple 40is trapped in the gap.

It should be noted that while spring 32 biases form tool 26 in theproximal direction, spring 84 bears against tab 86 on drag tool 70.Since the drag tool 70 is biased distally upon the proximal return ofform tool 26, the existence of a gap is ensured as spring 84 pushes dragtool 70 distally relative to the proximal motion of form tool 26. As aresult, a gap is formed between fingers 82 and lands 74 to allow thenext staple 40 to be captured and moved proximally within path 56. Whenforming a staple and moving form tool 26 in the distal direction, thedrag tool 70 contacts a stop at a certain point and, due to its thinconstruction at its distal end, allows fingers 82 to be pushedvertically out of the way of path 56 as the oncoming staple 40 movestoward anvil 78.

As the form tool 26 reaches its distal-most point having formed thestaple 40 by bending it around abutment surface 80, the ejector spring88, preferably having a pair of fingers 90, bears on the crossbar 76 ofstaple 40 and pushes it down and around abutment surface 80 to completethe staple ejection operation. It should be noted that the ejectorspring 88 is not operative to eject the staple until the trigger 16 isdepressed fully inwardly completing the distal range of motion of formtool 26.

Referring also to the detailed view, which is a portion of FIG. 1, theratchet mechanism, whose function it is to require the trigger 16 to befully depressed before it can be let out and vice-a-versa, to becompletely released before it can be depressed again, is illustrated indetail. The function of this mechanism is similar to that shown in FIGS.3 and 4 of U.S. Pat. No. 4,662,555. What is employed is a pawl 92 whichcan pivot on pin 94. Pawl 92 has a pair of ears 96 and an engagementpoint 98. Finger spring 100 has a tab 102 that rides between ears 96.Located within handle portion 12 is a bearing surface 104 on which point98 can ride. As the handle 16 is being depressed to move the drive block20 distally, such motion is permissible since point 98 is offset anddragging to the rear with respect to trigger 16. However, if the trigger16 is released before its completed stroke, the point 98 digs intosurface 104 and prevents outward movement of trigger 16. Ultimately,when the trigger 16 is fully depressed, the pawl 92 runs off beyond theedge of surface 104 causing rotation of pawl 92 on pin 94. Thereafter,as the spring 32 pushes the form tool 26 against the driveblock 20 in aproximal direction, point 98 is once again dragging allowing the trigger16 to come all of the way out from the handle portions 10 and 12.Similarly, when the trigger 16 is all of the way out, the pawl 92 runsoff the end of surface 104 and rotates about pin 94 to permitredepression of trigger 16.

The unique features of the staple pusher illustrated in FIGS. 2 and 4-8will now be described. The staple pusher 42 is shown in FIG. 2. It has apair of outriggers 106 that ride in grooves 54 (see FIG. 3). The leadingedge 108 of each of the outriggers 106 bears against the legs 52 of therearmost staple 40 in the staple track 38. Spring 44 bears on point 110.At the distal end of pusher 42 is the tab 112. Tab 112 has a roundeddistal edge 114 leading to a top 116 followed by a downwardly inclinedsurface 118.

The operation of these components is as seen in FIGS. 4-8. In FIG. 4,the last two staples remain in the inclined portion 58 of the stapletrack 38. Each of the staple legs 52 has a bottom bevel 120. The housing36 is formed having a curve 122 leading to a wall 124. As the pusher 42advances the second to the last staple (shown in FIG. 4), it starts topush it up curved surface 126. At that point, the staple pusher 42 isstill riding in the inclined portion 58 of staple track 38. Furtherdistal movement of pusher 42 (as shown in FIG. 5) displaces the secondto the last staple 40 upwardly into the form path 56. There, aspreviously described, when the form tool 26 makes its proximal returntrip, the gap between fingers 82 and lands 74 appears and then thesecond to the last staple moves up and is drawn back along path 56. Thebeveled ends 120 ride along wall 124 as an aid to the controlledrotation of the staple 40 fully into path 56 as form tool 26 concludesits proximal travel. The use of wall 124 to guide the staple 40 is to becompared to that illustrated in FIGS. 17-19 of U.S. Pat. No. 4,950,186.There, the staples do not bear on the wall but are engaged by anoverhanging ledge and retain in that position until the gap betweenfingers 82 and lands 74 engages crossbar 76 of the staple and pulls thestaple out from under the ledge and fully into the form path 56. Such adetail could be employed in the invention as an alternative way to guidethe legs 52 of the staple 40 as it is pulled into path 56.

FIG. 6 shows only one remaining staple which has a crossbar 76 incontact with curved surface 114. FIGS. 6 and 7 show the while theinclined path 58 transitions to curved surface 126 from the point ofview of support of crossbars 76, the staple pusher continues totranslate linearly along the plane of staple track 58. This continuinglinear translation with respect to the angled path 58 results in pushingcrossbar 76 up along curved surface 114. As form tool 26 movesproximally, the gap "appears," allowing upward movement into the formpath 56 where the staple crossbar 76 can be grabbed by the fingers 82 ofdrag tool as it moves proximally. After it moves upward into the gap,the staple is temporarily held there by surface 116. Once the crossbar76 is caught by the fingers 82 in the gap they make with lands 74, thestaple is pulled fully into path 56 as shown in FIG. 8. Ultimately, whenthe form tool 26 completes its travel proximally, the crossbar 76 downto beveled end 120 of the last staple 40 is fully within form path 56.As shown in FIG. 8, when the form tool is ready to advance distally toform the last staple 40, tab 112 still projects into the form path 56.Accordingly, the ramp surface 118 is provided so that the advancingstaple 40 has its crossbar 76 hit inclined surface 118. The staplepusher 42, once it is in the position shown in FIG. 8, is designed sothat tab 112 can be displaced downwardly, thereby allowing the laststaple 40 to advance to the end of form path 56. This bending actiongets tab 112 out of the way of form path 56.

FIGS. 9-11 indicate a snap fit between the trigger assembly composed ofhalves 10 and 12 and the nose assembly which is held within members 36and 64. The trigger assembly has a groove 128 formed behind fingers 130which are biased inwardly. Housing members 36 and 64 have a proximalflange 132. As the nose portion (housing 64 and 36) is inserted into thehandle portion 10 and 12, flange 132 displaces fingers 130 outwardly asshown in FIG. 10. Further insertion of the assembly into the triggerhousing allows the fingers 130 to snap back and engage flange 132. Atthat point, the nose is secured to the trigger housing 10 and 12 andcannot be removed. The modular design has several advantages. It reducesmanufacturing costs and inventory since individual modules can be usedin subsequent product designs. The use of the modular design also savescosts and molding parts since there are no undercuts or cores required.Further, the geometry of the design makes it a positive feedback system.Greater applied force leads to increased retention effectiveness. Thedesign also provides good strength with little deflection and offers thesecurity that the nose, once it is snapped into place, cannot be removedby the user.

The assembly of the nose to the trigger housing 10 and 12 can also beaccomplished in a manner that allows subsequent release. The noseassembly can be formed having a plurality of collet fingers, the edgesof which form a flange. The collet fingers can then be inserted into thetrigger housing to engage slots in the trigger housing 10 and 12. Oncethe collet members in the nose expand radially into the openings in thetrigger housing, the engagement is complete. Detachment then follows bydepressing the flanges at the edges of the collet fingers on the nosesufficiently inwardly so that the nose can be pulled out of the triggerhousing 10 and 12.

The positive displacement feature of the connection between the trigger16 and the drive block 20 is an improvement over the gear tooth assemblyused in U.S. Pat. No. 4,951,860. Some flexibility of movement isprovided between tab 22 and slot 24 to prevent the drive block 20 frombinding as trigger 16 pivots about pin 14. This design is capable oftransmitting considerable force and is simple to assemble, and can bemade of parts which are simple to produce and provide excellent "feel"and leverage.

Referring to FIG. 12, the importance of the thin distal end of the cover28 is illustrated. As shown in FIGS. 5 and 7, the staple pusher 42 mustpush the staple 40 above the cover 28 and into path 56. Thus, the use ofa thinner distal end 60 of the cover 28 reduces the height which thestaples must be raised to get them into path 56. It is the upward slope58 of the staple path 38 that allows the use of a thin distal end 60 ofthe staple cover 28.

It should be noted that the reliefs created by the use of outriggers 106on staple pusher 42 (see FIG. 2) allow staple pusher 42 to move alongthe inclined portion 58 beyond the point which it would normally havehit up against curved surface 122 or wall 124. This additional motionallows lifting of last staples.

The foregoing disclosure and description of the invention areillustrative and explanatory thereof, and various changes in the size,shape and materials, as well as in the details of the illustratedconstruction, may be made without departing from the spirit of theinvention.

What is claimed is:
 1. A surgical stapler, comprising:a housing; meansfor storing staples in said housing; means, at least in part, in saidhousing for forming staples, said means further comprising a formingpath; said storing means further comprising a staple track; said formingpath communicating with said storing means; a staple pusher operablealong said staple track; biasing means to selectively move said pusheralong said track; said biasing means having a proximal and distal end;mounting means in said housing for selectively fixedly mounting at leastone end of said biasing means to said housing in a plurality oflocations; said biasing means acting on said pusher, to selectivelyapply a variable preload force, resulting from the location of saidmounting means that is selected, through said staple pusher to a varietyof staple counts loaded into said staple track.
 2. The apparatus ofclaim 1, wherein:said pusher operable in said staple track from aproximal position where the track is loaded with staples toward a distalposition where the staples have been displaced from said staple track;means for camming the last remaining staples in said staple track assaid pusher approaches said distal position to impart an upwardcomponent of movement to those staples resulting from said pusher movingin a different direction than said staples.
 3. A surgical stapler,comprising:a housing; means for storing staples in said housing; meansin said housing for forming staples, at least in part, said meansfurther comprising a forming path; said storing means further comprisinga staple track; said forming path communicating with said storing means;a staple pusher operable along said staple track; biasing means toselectively move said pusher along said track and into said formingpath; said biasing means having a proximal and distal end; mountingmeans in said housing for selectively fixedly mounting at least one endof said biasing means to said housing in a plurality of locations; saidbiasing means acting on said pusher, to selectively apply a variablepreload force, resulting from the location of said mounting means thatis selected, through said staple pusher to a variety of staple countsloaded into said staple track; said staple forming means displacing saidstaple pusher out of said forming path as it approaches said distalposition, toward said staple to be formed, thus imparting a force onsaid staple pusher.
 4. A surgical stapler, comprising:a housing; meansfor storing staples in said housing, including a penultimate staple;means in said housing for forming staples, said means further comprisinga forming path; said storing means further comprising a staple track;said forming path communicating with said storing means; a staple pusheroperable along said staple track; biasing means to selectively move saidpusher along said track and into said forming path; said biasing meanshaving a proximal and distal end; mounting means in said housing forselectively fixedly mounting at least one end of said biasing means tosaid housing in a plurality of locations; said biasing means acting onsaid pusher, to selectively apply a variable preload force, resultingfrom the location of said mounting means that is selected, through saidstaple pusher to a variety of staple counts loaded into said stapletrack; said staple pusher having at least one camming surface thereon,said staple-forming means engaging said camming surface to cam thestaple pusher out of the forming path as said staple-forming meansadvances distally to form the penultimate staple in said track.